Improvement in artificial legs



STATES PATENT Onrrori.

DOUGLAS BLY, OF NEW YORK, N. Y.

IMPROVEMENT IN ARTIFICIAL LEGS.

Spccitication forming part of Letters Patent No. 57,666, dii-ted September 4, 1866.

To all whom t may concern:

Be it known that I, DOUGLAS BLY, Vot Newl York, in the county and State otl New York, have invented certain new and useful Improvements in Artificial Legs; and I do hereby declare that the following is a full and eX- act description thereof, reference being had to the accompanying drawings, making part of this speciiication.

Figure l is a central vertical section of my improved leg; Fig. 2, a plan of the foot, and showing more particularly the arrangement oi' the springs between the foot and leg; Fig. 3, a plan ot' a portion ofthe bot-tom of the foot, showing` the toe-joint arrangement; Fig. 4, a perspective view of the link-connection of the foot and leg; Fig. 5, a perspective view of one of the springs.

Like letters of reference indicate corresponding parts in all the ligures.

I obtained a patent, dated August 30, 1859, for an improvement in artificial legs, which consists, essentially, in the interposition of a rubber segment, forming a spring, between the foot and ankle portions. My present invention is an improvement on that device; and it consists, principally, in the employment of a series ot' springs instead of a solid segment arranged between the foot and ankle portions at suitable distances apart, said foot and ankle having a free universal motion.

As represented in the drawings, A is the foot, and B t-he leg, which, in general construction, do not dii'ter essentially from the corresponding parts in common use, except the foot has an oblong or oval socket, C, and the leg .a corresponding bearing, D, resting closely therein, these parts being formed concentric with the center of motion, so as to t and work closely and compactly together, whatever relative positions they may assume in the act of walking.

The foot and leg are connected by two links, E E, which form the center of motion. These are connected closely in the manner clearly shown in Fig. 4,'so as to allow the foot t-o tleX freely in the leg in every direction, but still limit rotary action ot1 the leo'. This construction ot' the double links allows any amount of compression of the springs at once by the slidingot the links on each ot-her as the leg and foot approach. Any turning motion of the leg is further prevented by the oval or oblong form of the socket and bearing G D. The links are secured in place by nuts I) b, or in any convenient manner.

l prefer to place the center of motion at some distance back of the center of the socket C, as clearly indicated in Figs. 1 and 2, in order to distribute the leverage properly upon the different springs. The leverage of the springs depends upon their distance from the center ot' motion. Some of the springs are placed 'at a greater and others at a less distance from thc center of motion, to counten balance the pressure which will be applied when in action. rlhe pressure on the front spring in walking will be as much greaterl than on the others as the length of the foot from the center of motion is greater than that ot' the sid`es or heel from the same point. Thus the center otl motion is located at such a position that the distribution of leverage upon the several springs will be in proportion, as nearly as can be, to the pressure that will be applied thereon in action.

A sufficient space is left between the bottom of the socket C and the bearing D to allow sufficient flexion in any direction. Instead Ot the employment ot' the solid block otl rubber between the foot and ankle, as in my former patent alluded to, Iv use in my present devicea series ot' separate springs, G G G, ot' any desirable number, arranged at suitable distancesapart around the center of motion within the socket C. I preer to make these springs simply of pieces ot' india-rubber; but any equivalent may be employed. ln order to retain them securely in place, I prefer to set them in sockets d d, formed either in the foot or ankle portion, or both, so as to retain them securely in place under all circumstances. These sockets I make of somewhat larger diameter than that of the springs, so that, as the latter expand by compression, space is left for such expansion; and I also bore or form them at an angle slightly outward from the line ot' the center of motion, as indicated in Fig. l, so as to compensate for the inward tendency of the pressure of the bearing D upon the springs. Otherwise, if the springs were set parallel with the line of the center of motion, thc turning action of the bearing in pressing down would produce a rubbin g action 2 sacca on the springs, and tend to injure them. The size of the sockets is also so relatively arranged with the springs that when the latter a-re depressed in any one direction they will be allowed to sink therein till the bearing D on that side comes in contact with the iioor of the socket, and they are thus secured from unnecessary pressure.

In adjusting the springs to the right position to receive the pressure of the leg properly I employT small disks or thicknesses ff Fig. 6, of buckskin or equivalent, which are placed in the sockets ot' the springs beneath them. They are also to be employed in adjusting' the springs if the springs should become shorter by wear or use. By this means the springs can be adjusted at any time and in the exactdegree desired.

The advantages of a series of springs arranged as above described are obvious. All undue rigidity is obviated. Each spring acting independently, the elasticity that is producedisequableaiuluniibrm. Thisalsosecures a greater degree of elasticity than could be otherwise produced when the pressure is applied in any given direction. It' the pressure is applied on any one side the springs yield only on that side, the opposite springs being passive.

It will be seen that I am also enabled to adapt the amount ot' elasticity to the necessities of the case. For instance, if the pressure is great, a larger number of springs may be employed; it' it is small, a portion of the springs may be removed. Thus I can adapt the arrangement for heavy or light use by simply employing a greater or less number ot' springs; also by using larger or smallersprings. The sockets cl d are especially adapted to this purpose, as they are made ot' larger size than the springs, and the latter merely rest in them. This arrangement of the springs enables the wearer to adjust the motions of his leg to suit his particular manner ot' walking, as he can increase or diminish the rapidity of motion by theinserting or removing ot' the v b'uckskin disks beneath the springs. In this arrangement the springs are employed in counection with a inlivcrsal-joint action ofthe foot and leg, resting laterally as well as longitudinally between the members. The links E E, constituting the center of motion, simply connect the parts, and by sliding one on the other, allow the leg to yield downward a certain degree when pressure is applied. In this manner there is no rigid ankle-joint, but the springs themselves constitute the joint and insure a free and easy action.

The toe-joint h is held in its socket by means of bolts z' i connecting therewith in any suitable manner, and secured to the foot by nuts 7tk. At a suitable position a plate, H, is attached to the bottom of the toe-piece near the joint, as shown in Fig. 3. This plate has a bearing, Z, below thejoint, with which hinges a bolt, m, passing back and connecting with a rubber or equivalent spring, I, by which the proper reaction is produced. By this arrangement it will be perceived that the leverage over the joint of the toe by means of the bolt m is considerable and sufficient at all times to produce .the necessary action of the parts. This advantage is attained in a great degree by the employment of the plate H, which is situated at the outside oi1 the toe.

A depression or cavity, 19, is made at thc top, between the toe and foot piece, of suiiicient depth to allowthe necessary movement of the toe, and a projection, q, of the ioot is made to project over the toe-piece, as represented in l, to such a degree as to cover it when straightened. By this means the space between the toe and foot is not left open, and there is no necessity of covering it with buckskin, as usual, but the whole is compact and fits tightly, and therefore the boot worn upon the foot will present a natural appearance.

Vihat I claim as my invention, and desire to secure by Letters Patent, is

1. A set oi' springs, Gr G, in combination with the leg A and foot B, ibrming a universal joint, substantially as speciiied.

2. Arranging the series of' springs G G near the periphery of the socket C, surrounding the center of motion, in. such a manner that the central space will be left open when said springs are employed between the foot and leg to produce reaction by compression, substantially as described.

3. The arrangcmentof the plate H, provided with the bearing l and the bolt m, connecting with the spring I, when used in combination with the toe-joint la in such a manner as to work over it and produce the necessary leverage, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

DOUGLAS BLY.

Witnesses R. F. Oscoop, J. A. Davis. 

